Municipal Affairs and Environment

Uranium in Well Water

Uranium is a naturally
occurring radioactive metal that occurs in low concentrations in nature.
It is present in certain types of soils and rocks, especially granites.
Uranium has the chemical symbol "U". The interim maximum
acceptable concentration (IMAC) of uranium in drinking water in Health
Canada’s Guidelines
for Canadian Drinking Water Quality is 0.020 mg/L
(milligrams per litre).

What are the known sources of uranium?

Naturally occurring uranium
in groundwater is a result of the dissolution of uranium bearing minerals
that have been in contact with groundwater for long periods of time.
Elevated concentrations of natural uranium in well water are more likely
to be found in drilled wells that obtain their water from the cracks and
fractures of bedrock, rather than dug wells or surface water supplies.
Uranium can also be found in the environment as a result of human
activities such as mill tailings, emissions from the nuclear industry, and
the combustion of coal and other fuels.

What are the environmental health concerns of uranium?

Naturally occurring uranium
has very low levels of radioactivity. The chemical properties of uranium
in drinking water are of greater health concern than its radioactivity.
Most ingested uranium is due to food intake with lesser amounts
accumulated from water or from the air. Uranium mostly is rapidly
eliminated from the body, however a small amount is absorbed and carried
through the blood stream. Studies show that elevated levels of uranium in
drinking water can affect the kidneys. Bathing and showering with water
that contains uranium is not considered a health concern. There is
inadequate data available to evaluate the carcinogenicity of ingested
uranium.

Where have high uranium levels been found in Newfoundland and Labrador well waters?

Research on uranium is
being carried out by the Department of Municipal Affairs and Environment, and
the Geological Survey of Newfoundland and Labrador, Department of Natural
Resources. There have been a total of 5 exceedances on the island portion
of the province. To date, no uranium exceedances in well water have been
found in Labrador. A uranium risk map has been created by the Geological
Survey using a combination of bedrock geology, lake sediment geochemistry,
the Mineral Occurrence database system, and maps of airborne geophysics.
Any known occurrences of uranium in well water have also been added to
this map. As with arsenic in groundwater, elevated uranium levels in
drinking water can be found outside of the areas shown on the map, and
water from most wells in the areas indicated as higher risk do not contain
elevated uranium. The map shows:

areas of the
province interpreted to have higher risk of uranium in groundwater